Ion or plasma trapping is well known. Penning traps are routinely used in non-neutral plasma physics for study of basic plasma physics, fluid mechanics, atomic physics, nuclear physics and particle physics. These traps operate under vacuum and trap the fully ionized plasma in a magnetic field. Vacuum conditions are well known and are typically about 10.sup.-7 torr or less. The presence of neutral gas tends to disrupt the behavior of a fully ionized plasma whereas behavior of the fully ionized plasma is recovered upon reduction of neutral gas pressure. Penning traps are sensitive to mechanical precision of surfaces.
Paul traps relying on radiofrequency energy are used to trap weakly ionized gases. However, Paul traps can only trap large particles at pressures approaching atmospheric pressure. Further, a Paul trap must remain substantially symmetrical if scaled up.
Accordingly, there is a need for an ion trap that is robust, insensitive to symmetry and pressure.